The handover (or handoff) procedure is a means to continue a call when a user terminal crosses the border of one cell into another. In a cellular network, a cell has typically several neighbouring cells. The basic concept of a handover is that when the user terminal moves from the coverage area of one cell to another, a new connection is set up with a target cell and the connection with the old cell may be released. In many cases, an inter radio network controller hard handover is carried out.
In inter radio network controller (radio network controller=RNC) hard handovers, the main problem is to find a right time for switching from a handover source RNC to a handover target RNC due to delays in the handover process.